So my scroll stopped working on my labtop when I installed the new update (8.1) about 3 weeks ago. I've tried going to mouse setting and all that, but its not doing anything. so does anybody know how to turn in back on?

Usually this issue causes due to mouse/touchpad driver compatibility issues or due to hardware issues. To assist you further with this issue, I would like to know some information regarding the same.

1. What is the make and model number of the computer?
2. Do you get any error code or error message?

I would suggest you to try the following methods and check if it works for you.

Method 1:
Run the Hardware and Devices troubleshooter and check if it helps.

Follow the steps to run the troubleshooter:
a. Press Windows key + W on your keyboard.
b. Type Troubleshooting and click Troubleshooting.
c. Now type Hardware Troubleshooter in the search option.
d. Click on Hardware and Devices troubleshooter to run the troubleshooter.

Method 2:
Try reinstalling the mouse/touchpad drivers from the computer/mouse manufacturer's website and check if the issue persists.

Step 1: Uninstall the driver:
a. Press Windows key + X on the desktop Screen and select Device manager.

b. Expand the device and right-click on driver and select ‘uninstall’.

Step 2: Download and install in compatibility mode:

If they have only Windows 8 drivers, then trying installing it in Windows 8 compatibility mode.

Follow these steps to install the drivers in compatibility mode and check if that helps.

a. Download the driver from the manufacturer’s website.

b. Right-click on the driver setup file and click on ‘properties’.

c. Click on the ‘compatibility’ tab and check the box ‘Run this program in compatibility mode for’ and select Windows 8 operating system from the drop down menu.